Apparatus for filtration



to 1 g l p 6 927 N. c. cHRlsTENsEN APPARATUS FOR FILTRATION s sheets-Sheet 2 Filed Jan. 19. 1921 Se t. p 6 1927 N. c. cHms'rENsEN APPARATUS vFR FILTRATION Filed Jan. 19. 1921 f 5 Sh eets-Sheet 5 ffm/m? "7T/M5 C.

WFA/55555,

Patented Sept. c, 1927.

UNITED 4s'rafras NIELs c. cHRIs'rENsEN, or sami LAKE crm, UTAH.

APPARATUS FOR IliIL'.DlwiAllPION'.

Appunti@ mea January 1e, 1921. serial 1ro. 488,372.

This invention relates to improvements in vacuum filters and methods of vacuum filtration. It is the object of the invention to recure a combination of all the separate advantages of the different types of vacuum 'filters combined in a simple continuously operating device. i

In the two types of vacuum filters commonly used each have advantages and disadf vantages not possessed by the other. The disadvantages of the leaf or basket type of filter are that, it isintermittentin operation, requires large storage tanks, the basket of filter leaves must be handled by suitable lifting devices and cranes or the pulp and solutions must both be handled by a relatively complicated system of storage tanks and pipes and valves, either of which require constant attention and labor, the capacity per square foot of filter medium 1s low due to the relatively thick filter cake which must be used due to the intermittent operation. The main advantages of this type of filter are the thorough Washing of lthe filter cake which may be secured and that it is possible to use a counter-current method of Washing.

The advantages of the rotary type of filter of either the drum or disk type are its continuous automatic operation which r.e quires little attention, and the high capacity per unit area ,of filter surface due to the continuous automatic operation which makes possible the use of a relatively thin filter cake. The main disadvantages of this type l ofV filter are the difficulty of securing a good Wash and the practical impossibility of using a counter-current method o'f Washing as the 'liquids for Washing must be applied by means of sprays. y

It is the object of my invention to secure all the advantages of these types of filters together with other advantages not possessed by either of these types,"and to do this in a simple continuously operating automatic device requiring a minimum of attention in operation and easily adjusted and repaired.

My filter is continuous and automatic in operation and has therefore all the advantages of the rotary drum or leaf filter. Its

method of Washing lis similar to 'the intermittent leaf or basket type of filter, 1n thatv the filter cake is surrounded by the Wash solutions during the washing of the cake, and

"Y it has therefore the main advantages of thisr i type of filter. My filter also has the great advantage that a counter-current method of Washing may be Avery efficiently used. It has also the greatV advantage that it may easily be made acid proof. It is also very simple in construction and easily repaired.

The invention consists in general of a number of separate vertical chambers open at the bottom and containing a number of vertical filter leaves or tubes. The chambers are -arranged so as to form a practically continuous ring about a central vertical axis around which the chambers move in an annular path. v A central automatic valve controls tht application of suction and pressure and the withdrawal of solutions from the sets of filters in each chamber. Each chamber thus forms lan independent unit. The filter tanks consist preferably of an annular trough divided into separate sections vfor containing the pulp, the Wash solutions, and the dischargedcake. The surface of the pulp and solutions is maintained constantly at practically the same level in all the compartments at all times. Suitable agitators prevent settling of the pulp. The suction chambers of the filter are arranged so that the loWer part of each chamber dips slightly into the pulp and solutions in passing around the annular path, the main parts of the filter chambers being entirely above the level of the pulp or solutions in the annular; trough or'tank. As noted the chambers are entirely closed except at the bottoms, which dip into the pulp or solution at the places Where the vacuum is applied to the filter media. When a vacuum 1s applied inside of the filter media and the chambers dip into the solution or pulp, the pulp or solution is dra-Wn up into the chamber filling it and surrounding the filter media. In this Way the solution is drawn through the. filter medium and the cake is formed thereon, and

.pulp and wash solution;

ofthe method of operation of the filter which may be constructed in general in three different ways to suit the conditions under which it is designed to operate. In one arrangement the filter chambers are connected so as to form a rigid structure or are merely divi.

practically noV tendency forv any flow from one compartment ofthe tank into another through the' notch in the upper edge of the portions through which the lower part of the ring of filter chambersmoves. In this' case the cake is preferably discharged into water (or solution) which is kept -at the same level in the.discharge'compartment as the pulp and solutions in their compartments. This arrangement of my filter is especially applicable for simple filtering without washing. s

In another arrangement, the partitions which separate the filter tank into compartments for pulp solution and discharge ex- .tend above the level of the pulpA and solutions and the cakes are discharUed dry, i. e. not into water or solution, and the lower part of the filter-chambers must be lifted over each of these separating partitions as the filter chambers revolve.v In one of these arrangements each chamber is lifted separately necessitatin a flexible connection hose or flexible jointed pipe) between each lter chamber and the central valve.- In the other of these arrangementsthe lower part of each chamber is supplied with an exten-` 'sion which ma be automaticallyI lifted up over. the partitions and be let down -into the pulp or solution so that the main art of each chamber is not.. lifted and ris rigi ly connected to the central `supporting mechanism and valve. This is accomplished in either of-two ways, by means of a flexible extension which may be lifted over the partitions `and then be dropped into the pulp or solution or by means of a rigid extension making a close fit on the main part of the chamber or connected thereto by a fiexible membrane. p

In a third general arrangement no part of the filter chambers arelifted over the partitions but pass through a notch therein and the solutions and pulp in adjacent sectors of the trough are kept separate and their mixing prevented by suitable auxiliary overflow sectors at. both ends of each main sector from which the liquid overflowing through the notches is returned to the main sector.

As will be noted all these arrangements are essentially the same, the entire general arrangement of chambers,'driving and supporting mechanism central valve and trough being practically the same, with slightly different methods of. bringing the lowel parts of the filter chambers into the liquids in separate sectors of the trough and at the same time keeping these liquids separate.

rlhe filter construction may be of two different types, the common type consisting of leaves lor tubes of suitable shape around the outside of which the filter cake is formed, or tubes of different suitable shapes on the inside of which the cake is formed. y

The foregoing general statements will be made clear by the following more detailed description of the accompanying drawings v and methods of operation of the invention.

Fig. I shows av general plan of the arrangement of the filter and Fig. II a vertical section on a diameter and Fig. III a vertical section on a circular line A`A of this plan,

-showing the general arrangement of filter chambers, central valve and trough for pulp and solution. The section on A-A shown as a plane surface, the circular surface being straightened to a plane. In Fig. I the quadrant M shows a horizontal section on B-B, quadrant N a section on (lL-C, quadrant O a lan view and quadrant P vshows the troug and driving mechanism.

Figs. I, II and III show the simplest arrangement in which the bottom of filter chambers move at all times in the same horizontal plane i. e. are not lifted over any partitions.

Fig. IV' shows a vertical section on a circular line A-A illustrating a means of discharging a dry-cake from the foregoing arrangement and means for preventing mix.- ing of solutions from adjoining sections o the trough.

Fig. V shows a vertical section on a diameter D-D showing this notch in the trough through which the lower part of the filter chambers are passed in this method of arrangements of the invention.

` Figs. VI. VII, VIII and IX show partial vertical sections on diameters of the apparatus illustrating various methods by,which the lower parts of the filter chambers may be lifted over theeJ partitions in the trough. Figs. X, XI, and XII are vertical sections of filter chambers showing different forms of filter medium and different arrangements of these in the filter chamber which may be used. Fig. XIII a vertical section on acircular line A--A showing the partitions over which the lower part of the' chambers must be lifted and indicating the lifting rail. Fig. XIV isa horizontal section of the cenassises Y tralautomatic valve illustrating the connecand move in an annular path around this axis. Rotating aboutthis central aXis and connected with .the spider o`r Wheel supporting the filter chambers isthe rotating part (6) of the central automatic valve (7). The

'stationary part (8)-of this valve is supported by the central column (5) so that 1t is symmetrical around the same vertical axis as the wmoving part (6). The moving part (6) of the valve (7) is connected to each of the filter chambers 1) by the pipes (9) which revolve with the chambers (1) and moving part (6) of the valve and through which vacuum anc1 pressure are applied to the filter medium in each chamber and through which the-solutions are withdrawn. The supporting wheel or spider (4) is turned on the central column (5) by a suitable driving mechanism (10). Beneath' the ring of filter chambers is a suitable, preferably annular, trough (11) in which the pulp to be filtered'and the different wash solutions are contained. The trough is divided into separate compartments forthis purpose by the radial partitions (12).

The central automatievalve (7) consists of a moving part (6) to which the pipes (9) from each filter chamber areconnected each one preferably havingl its individual outlet hole (13) all of which are symmetrically arranged in a circlearound the central *vertical axis of the valve. The moving part (6) of the valve and the stationary part (8) meet each other in smooth plane surfaces (or valve face or seat) in the horizontal plane C--C and are held together under sufiicient pressure to form a tight joint by a suitable spring (14) around the central col- 'umn (5). The stationary part"(8) of the valve has an annular slot or trough (15) whose central line` is approximately of the same diameter as the circle passing through the centers of the holes (13). The slot (15) and the holes (13) open into each other on the surface or plane C-Cy between the sta-` tionary and moving parts of the valve 6A and 8 respectively. The fillers (16) divide the annular slot or trough (15.) into separate sectors (17 from which the openings (18) lead to the outside pipes (19) through which the vacuum is applied and through which the solution is withdrawn and to the outside pipes (20) through which air or water under pressure may be applied to the filter medium to release the cake. The .numberl and arrangement ofthe dierent sectors (17) of the stationary part (8) of the v alve and their outside pipes (19) and (20) will depend upon the nature of the work to which the filter is applied and may be either a simple operation in which only two sectors (17) and a single solution and vacuum pipe (19) and a single pressure pipe (20) may be used for a simple filtration, or a large number of such sectors (17) and pipes (19) arranged for counter-current washing by filtration., The operation of a valve of this kind is so well understood that a more detailed del scription is unnecessary, the general arrangement being such that the holes (13) connected with cert-ain of the filter chambers (1) open into suitable sectors (17) as the chambers move around the circle so that vacuum and pressure are applied as desired in different parts of the path according to the particular filtering operation being conducted.

The filter chambers (1) and filter medium may varyV in construction, the essential requirement being that the chamber is closed except at the bottomA which dips into the pulp or solution and that 'the vacuum and pressure) is applied to the open part of the chamber through the filter medium. Two

different types differing somewhat in construction but similar in operation, maybe used. The type illustrated in Figs. X and XI consists ofval chamber (1) open at the bottom (2) in which the filter leaves or tubes 3) are suspended. Fig. X shows a design for use with fil-ter tubes (3). The filter tubes (3) are closed at the bottom and are held in position by the-ring (21) at the upper end which is held between the plate (22) through which the tube passes and the upper plate (23). The tube is closed at the upper end by a suitable cork or plug (24) through which the pipe (25) passes. The pipe (25) extends from near the bottom of the filter tube (3) through the plate (23). The plates (22) and (23) are clamped together between the-lugs (26) and (27) on the in'idc wall ofthe chamber 1) and the cover `V plate (28). The cover plate 28) is bolted'to the walls of the chamber 1) by suitable bolts (29) and leaves an open space y(30) above the llo plate (23) into which. the pipes (25) open.

The channel l(31) opens from this space 30) into the vacuum and pressure'pipes 9), through which vacuum and pressure are applied. This type of construction is especially well suited to being made acid proof since tlie wall (52) and cover plate (28) of the chamber (1.) may be made ofI any suitable material such as porcelain, lead, bakelite, bronze, or other suitable acid proof material, and the filter tubes (3) may be made of crushed and graded particles of fused alumina or uartz moulded and baked with suitable bon ing material to make a porous medium, or of porous porcelain, acid resisting metal, cloths, etc., and the plates (22) and (23) of such materials-as bakelite, porcelain, ronze or other suitable material. The tube (25) may be of glass, porcelain or other` acid proof material, and the cork (24) of rubber, acid-proof cements or other suitable material. In work Withstrong acids such as HCl and HSOA, and with acid brine solutions, extending over a long period, I have found porous tubes of fused alumina to be a most excellent filtering medium, being relatively strong, resistant to the action of strong acid solutions and an excellent filtering medium of low resistance which does not clog up or become obstructed like many other filter media. As will be readily seen tubes are easily removed and replaced by removing the cover (28). p

The construction for using filter lleaves instead of tubes shown in Fig. XI is similar to that just described except that only a single plate (23) may be used through which the pipe (25) passes and is held in'place by the lock nut (32) and lug (33) on the pipe (25).

The other type of arrangement referred to above is shown in Fig. XII. In this case the tubesv (circular or rectangular preferably the former) are closed at the upper end and held in position between the lower perforated plate (34) and the upper perforated late (34a) through which the tubes pass.

aid plate (34a is held in place by the cover plate (28) as before described. The openmg (31) connects with the vacuum and pressure ipes (9). As will be seen in this case the lter cake is 'formed inside of the tube instead of outside. The action of the filter chambers is as follows: When the vacuum is applied from the central valve (7) through the pipes (9) and passa-ge.D (31) to the space (35) enclosed by the filtermedium, vand the lower part of the chamber (1) dips slightly into the pulp, the pulp is drawn up into the open space (36) around the filter medium and solution is drawn through the filter. medium and a` cake formed thereon. To wash this cake the lower part of the chamber is dipped slightly into the wash solution and the vacuum applied as before and solutionis drawn up into the space (36) and through the filter cake. To discharge the cake, air (or water) under pressure is applied from-the central valve (7) through the pipesl(9) and passage (31) to the space (35) enclosed by the filter medium andthe cake thus loosened and dropped fromthev filter medium.y

The filter chambers (1) shouldpreferably be separate units readily attached to and detached from the wheel or supporting frame (4) and pipes (9) for repair, and the pipes (9) should preferably each be supplied with a suitable valve (37) by which vthey may be closed so that any filtering chamber may be removed and repaired without interfering with the operation of the apparatus as a whole.

As previously stated, in the forms of the apparatus used for washing as well as filtering the pulp and the different solutions in the trough (11) may be kept separate by suitable radial partitions (12) which may or may notextend entirely above the solution or pulplevel. In the former case the lower part of the filter chambers (1) must be withdrawn from the pulp or solution and lifted over the partitions and dipped slightly into the solution on the opposite side in passing around the annular path. This may be accomplished in two different ways, by slightly lifting and lowering the entire filter chamber (l) or by the lifting of a lower portion of the chamber which is connected with the main upper part of the chamber in such `a manner as to be movable and yet-so as to form a continuous closed space so the vacuum may be applied and solution and pulp drawn up into they chamber as previously described. If the filter chamber is lifted as a whole a flexible joint or hose connection must be used in the pipe (9). The lifting of the chambers (1) may be accomplished in the manner shown in Fig. VI. The chambers are held to the rim (38) of the supporting wheel or spider (4) by suitable guides (39) in which the sliding piece (40) attached to the chamber (1) may slide -up and down. A suitable stop or lug in the `guides holds the chamber at its lowest position so that the lower part of the chamber (l) dips slightly into the pulp or solution. At the partitions the elevated portion of the guide rail (41) (see Fig. XIII) lifts the chamber 1) upward in the guides (39) and over the partition (12) and allows it to drop to its lower position again.

'Ihe use of a movable lower portion of the chamber may beI accomplished in several ways as shown in Figs. VII, VIII and IX. Fig. VII, shows my preferred method. In this construction a loose fitting sleeve (46), surrounding the lower part of the chamber (1) and held in place by suitable rods (44) and guides (45) so that this sleeve (46) may be moved up and down by the guide rail (41) as these come in contact withthe lifting lug (43) on the sleeve as the chamber passes around the circle is used. The sleeve (46) `reame@ tion and when the vacuum is applied, the solution or pulp is drawn' up inside the chamber (1) and closesthe space (48) `between the ,sleeve (46) and chamber wall (l) .and traps the air enclosed in the space (49) :and prevents the upward iiow of pulp andy solutionin this' space and thus prevents their coming into contact with the membrane (47) In this way the pressure both inside and outside :of the membrane (47)l is also made. practically equal and the membrane is not subjected to any severe strain. When the chamber (1) reaches a position near a partition walln (12) over which it must be lifted, thek guide rails (41), or other lifting device,

- coming in Contact with theilifting lugs (43) on the sleeve (46) lift the sleeve up out of the solution or pulp and over the partition and then allow the sleeve to pass downward and dip into the solution or pulp on the other side of the partition as the chamber moves around the circle. 4-Only a very small up and down movement of the sleeve (or of any of the lifting devices) is required since the pulp or solution level may be maintained near the top of the partition and the bottom of the'sleeve (46) or chamber (1) dips but very slightly into the pulp or solution. The device shown in Fig.` IX is similar to the one just described except that the sleeve (46) has a closeiitting machined `or packed joint between it and the main part of the chamber. Another method or construction is shown in Fig. VIII in which there is a flexible extension (50) lfrom the bottom of the chamber (1) supported by suitable rigid rings (51) so as to prevent collapse of the flexible tube and held in position by suitable rods '(44) which extend through guides (45) and lift-ed by means of the lifter lugs (43)` and thev guide rails (41), or other lifting devices, as previously described. The action of these arrangements is similar to that de scribed for Fig. VII.

If it is not desired to use any of the lifts ing constructions such as described, the pulp i and different solutions may be kept separate,

with no mixing andthe filter cake may be discharged dry (i. e. not into ythe solution). without any lifting of the chambers or any lower part thereof, by the means illustrated in Fig. IV, which is a vertical sect-ion .on a. b

circular line within the tro-ugh, the section being shown as having been rolled outplane, and in Fig. V which is a partial vertical section on a diameter. @In this method ofY construction the bottom of the chambers all. move in the same horizontal plane and pass through a. relatively closely fitting notch (52) in eac-h of the partltions .(12) Extend-v ing out into each pulp or solution sector 67) i of the main trough (1l) from thenotch 52 i at each end of the sector is a shallow troug (53) of the same shape in vertical sectionfas the notch (52) through which trough (53)' the chambers (1) pass toward or away from. the `notch (52) Figure 4., In this case'vthe solution or pulp levels are maintained slightly above the bottom (54) of the trough (53)V or notch and above the bottom of the chambers (1). This causes a'slight leak of solution or pulp through the trough (53)l and out of the notch 52) between the lower part of the chambers (1) and the bottom and sides of the trough (58). rIhis overow from the notch in the ends of the sectors (67) passes into the overdow sectors (55) and is returned to the sector (67 from which it came by a suitable pump (56) (or other lifting device) through suitable pipes (57) and holes (58) as indicated by the arrows (59). '.lhe trough (56) and bottoms of the chambers (1) should form a comparatively close itso that the leak through the notches will be relatively small under the slight head required for the dipping of the lower ends of the chambers slightly into the pulp or solution andthe capacity of the pump (56) should be ample to care for this leak. A, suitable overow f (60) from each 'overflow -sector (55) to a supply tank should preferably be provided and the pulp or solution for each sector 67 should preferably be supplied'witha constant regulated supply from this supply and storage tank through a suitable pipe or launder (62) (Fig. V). In this way a constant level in the sectors (67 and 55) may be maintained and the lower part of the chambers (1) may be kept immersed in solution or pulp in the sectors (67) without any lifting of thechambersor any mixing of different pulps or solutions. rIhe level of pulp in the overiiow sectors (55) should preferably be considerably below the levely in the main sectors (67). The manner of discharging the dry cake fromv such an arran ement is the same as just described the v disc arge hopper (61) having overow sectors (55) and notches (52) and troughs (53) on' both ends so that the chambers (1) may pass out of the sectors (67) and'over the" hopper (61)- where the filter cake isdis charged and falls intofthe hoppers (61)` without any How of solution into this-hopper..V

The operationk of my invention for dif-l ferent purposes in different applications willn e so apparent from the foregoing that a,-

very. brief general description of dierentiV met-hods` of operation willbe sucient for those familiar with ilter devices.

For asimp1e filtering operation without washin (i. e. dewatering or clarifying)` inl which t e filter cake' may be' discharged into,v the liquidand removed from a hopper in theI trough (l1)l by a sultable underflow device or drag, t e simplest `rform` ofl chambers, trough and'valve are used. The chambers in this case are without lifting devices of` any kind and move around the circle dipping slightly into the liquid at their lower pomts -fof during the entire cycle. The trough is also without partitions above the surface of the liquid, but may have` partitions beneath to form a discharge hopper for the removal of i the filter, or to prevent excessive mixture of solution or pulp in different parts of the trough. The central valve (7) applies the vacuum during the entire movement of each chamber (l) around the circle except above the discharge hopper where 'pressure is a lied to release the cake which fallsof t e ter medium and settles into the dischargel hopper and is removed in a wetl condition. l

For combined filtering and washin operations the pulp and solutions should t(Ine separated and kept from mixing and in this case partitions are necessary. In this case one of the lifting devices must be used if the "parf titions extend above the liquid level or overfiow and return devices may be used in each sector as described and the lifting devices be doneoaway with. In any case the operation is similar in that the lower parts of the chambers dip into the pulp or solution in each sector and pass from onesector to another around the circle and discharge a dry (i. e. free from excess moisture) filter cake without mixture of different liquids or fiow of liquid into the discharge sector. The vacuum and pressure are applied by the central valve at suitable points in the passage of the chambers around the circle. The drying time between sectors may be regulated by the length of time the bottom of each chamber is kept out of the liquid between the sectors by means of the adjustment of the length ide rail in the lifting devices and the wi th of overflow or separating sectors (55) between the pulpl and solution sectors (67). The length of drying before dischargin the cake may be regulated b the length o the discharge space (61). he application of the vacuum is of course regulated by the oentral valve to correspond to the foregoing. For counter current washing the solutions are passed from sector to sector in counter current to the movement of the chambers. It will be apparent that my invention is esecially well suited for counter current washmg since any number of sectors maybe used and the central valve may readily be constructed to conform to these.

From the fore oing description andthe drawings it will e seen that my device secures and combines all the advantages of both the intermittent and continuous rotary vacuum filters, without their disadvantages, in a compact automatic filter device which is simple in construction and operation and might be used in my inventio:

tion to give all the possible variations in easily and quickly repaired.

As it will be apparent that 1t wouldl be impossible in the scope of a patent applicclatail of construction and operation which and itis also vwithin said chamber vertical spaces which are entirely enclosed except for openings through which vacuum and pressure may be applled thereto, together with means for dipping the lower end of said chamber4 slightly into liquid pulp to be filtered.

2. The apparatus for separating liquids from finely divided solids by filtration which consists of' a lvertical chamber closed at the sides and top and having suspended therein vertical partitions of filtering mediuml arranged sovas to form of a portionof the space within said chamber vertical spaces which are entirely enclosed except for openings through which vacuum and'l pressure may be applied thereto together with means.

for dipping the lower end of, said chamber slightly into liquid pulp to be filtered, all arranged so that when the lower endl of said chamber is dipped slightly into a liquid pulp and a vacuum'is applied to said enclosed spaces that said liquid pulp will be dra-wn up into and fill the space within said chamber outside of said enclosed spaces and liquid will be drawn through said partitions of filter medium into saidenclosed spaces and solids in suspension in said liquid pulp will be deposited on the outside side of said partitions of "filtering medium.

3. The apparatus for separating liquids from finely divided solids by filtration which consists of a vertical chamber closed at the sides and top and having suspended therein vertical partitions of filtering medium so arranged as to form of a portion of the space within said chamber vertical spaces which are entirely enclosed except for openings through whichvacuum and pressure may be applied thereto, together with means for dipping the lower end of said chamber slightly into liquid pulp to be filtered, all arranged so that when the lower end of said chamber is dipped slightly into a liquid pulp and a vacuum is applied to said enclosed spaces that said liquid. pulp will be drawn. up into and fill the space within said chamv ber outside of said enclosed spaces and liquid will be drawn through saidy partitions of filter medium into said enclosed spaces and solids in suspension in said liquid pulp will be deposited on the outside side of said partitions of filtering medium, and also arranged p mamen ,n

so that When a fluid under pressurefis thereafter supplied to said closed spaces that said filter cakes will be loosened from the outsidep of' said partitions of filter medium and will bc discharged through the open bottom of said chamber. U

4. The apparatus for separating l1 uids from finely divided solids by filtration W ich through which vacuum and pressure may e applied thereto, and said chambers arran ed in a ring and attached 'to a suitable driving' and supporting mechanism so as to be moved through the same vhorizontal annular path around a central vertical axis; a central automatic valve having a part thereof` arranged to revolve around said bentral vertical axis with said chambers, said revolving part having separate ports therein corresponding to said chambers and connected by suitable pipes to said enclosed spaces in said. chambers and arranged so that vacuum and pressure may be automaticallyapplled to said enclosed spaces in each of said chambers during the passage of said chambers through certain parts of said annular path; together with an annular trough parallel to and beneath the annular path of said chambers and arranged to maintain liquids therein at a relatively constant level and at such level v that the lower parts of said chambers will dip slightly into said liquids in passing around said annular path.`

5. The apparatus for separating liquids from finely divided solids by filtration which consists of a number of similar vertical chambers, each of Which is closed at the sides and top and has suspended therein vertical partitions of filtering medium so arranged as to form of a portion of the space Within said chamber vertical "spaces whichl are entirely enclosed. except for openin s through which vacuum and pressure may e `applied thereto, and said chambers arranged in a ring and attached to a suitable driving and supporting mechanism so as Vto be moved through the same horizontal annular pathv around ,a centralvertical, axis; a central .automatic valve having a partthereof arranged to revolve around said central ver-l tical axis With said chambers, said revolving part having separate ports therein correspondingto said chambers and connected by :suitable pipes to said enclosed spaces in said chambers and arranged so that vacuum'and pressure may be automatically applied to said enclosed spaces in each of said chambers during the passage'of said chambers through certain parts of said annular path; together vat such level that the lower 'pension in saidliquid will `form filtei;

on the sides of saidfilter media in the open with an annular, trough parallel to and beneath the annular path of said chambers and?.

arranged to maintain liquids therein at a relatively constant level and at such level that the lower parts of said chambers Will `'dip slightly into said liquids in passing around said annular path; means for applying vacuum and pressure through said automatic central valve at predetermined places in said path; means for continuously supplying liquid trough.

6.- |The apparatus for separatingliquids from finely divided solids by filtration which consists o fra 'number of similar vertical chambers, each of `which is closed at the sides vand top and has suspended therein pulp to be filtered to said vertical partitions of filtering medium `so of arranged tol revolve around said central vertical axis with said chambers, said revolving part having separate ports therein corresponding to said chambers and conne-cted by suitable pipes to said enclosed spaces in said chambers and arranged so that vacuum and pressure may be automatically applied to said enclosed spaces in each of said chambers during the passage of said chambers through certain parts of said annular path; together with anannular trough parallel to and beneath the annular path of said chambers and arranged to maintain liquids therein at a relatively constantlevel and oparts of said' chambers will di slightly into said liquids in passing aroun said annular path; means for applying vacuum and pressure through said automatic central valve at predetermined places in said path; means for continuously supplyingrliquid pulp to be -ltered to said trough all arranged so `that when liquid pulp 'to be 'filtered is continuous-V ly supplied to said trough and said chainbers are continuously moved in one direction around said annular path by the application of ower to said supporting and driving mec anism and vacuum and pressure are supplied 'to said central automatic valve,th'at in certain parts of the path of said 'chambers Aliquid pulp will be drawn up yinto and fill s the open spaces in said chambersand liquid lill) will be drawn through said partitions of filter of medium-into said enclosed spaces vand be Withdrawn therefrom and solids in suscakes mamas liquid to be filtered is continuously supchambers above said sectors containing liq-y uids, said liquids will be drawn upinto 'and' ll said open spaces in said chambers and liquid will be drawn through said partitions of filter medium into said enclosed spaces and be withdrawn therefrom and solids in suspension in said liquid willV form filter cakes on the sides of said filter media in said open spaces, and in a part of said path above said discharge sector the filter calres thus formed will be discharged from said chambers into said sector.

v l0. The apparatus for separating liquids 'from finely divided solids by filtration which consists of a number of similar vertical chambers, each of which is closed at the sides and top and has suspended therein vertical partitions of ltering medium so arranged as to form oi a portion of the space within said chamber vertical spaces which are entirely enclosed except for openings through which vacuum and pressure may be applied thereto, and said chambers arranged in a ring and attached to a suitable driving and supporting mechanism so as to move though the same horizontal annular path around a central vertical axis; a central automatic valve having a part thereof arranged to revolve around said central vertical axis with said chambers, said revolving part having separate ports therein corresponding to said chambers and connected by suitable pipes to said enclosed spacesin said chambers andarranged so that vacuum and ressure may be automatically applied to sald enclosed spaces in each of said chambers during the passage of said chambers through certain predetermined parts of said annular path; together with an annular trough parallel to and beneath the annular path of saidV chambers and arranged to maintain liquids therein at a relatively constant'level and at such level that the lower parts of said chambers will' dip'slightlyqinto said liquids in passing around their lsaid annular path; a central automatic valve hav- ,ing a part thereof arranged to revolve be automatically applied to said enclosed spaces in each of said chambers during the passage of said chambers through certain predetermined .parts of said annular path,

an annular trough beneath said annular path with radial partitions therein dividing said trough into separate sectors some of which are arranged to contain liquids and one ot which sectorsis arranged to receive .filter cakes dropped from said chambers; means for passing said chambers over said artitions and allowing the lowerparts o said chambers to dip into the liquids in said sectors in passing around said annular path.

1l. rlhe apparatus for separating liquids from finely divided solids by filtration which consists of a 'number' of similar vertical chambers, each of which is closed at the sides and top and has suspended therein vertical partitions of filtering medium so arranged as to form of a portion of the space Within said chamber vertical spaces which are en-A tlrely closed except for openings through which vacuum and pressure may be applied thereto, and said chambers arranged 'in a ring and attached to a suitable driving and t arranged so that vacuum and pressure may be automaticallyy applied to said enclosed spaces in each of said chambers during the passage of said chambers through certain predeterminedl parts of said annular path; together with an annular trough parallel to and beneath said annular path with radial partitions therein dividing said trough into separate sectors some of which are ar' ranged to contain liquids, `and one pf which is arranged to receive iilter cakes dropped.

from said chambers, means@ to maintain liquids thereinat a relatively constant level, and means for passing said chambers over said partitions and allowing' the lower parts of said chambers to dip slightly into said liquids in passing around said annular path;

means for applying vacuum and pressure through said automatic central valve; means for continuously supplying liquid to be filtered to said sectors for containing liquid.

12. The apparatus for separating liquids 'l from finely divided solids by filtration which consists ofv a number of similar4 vertical chambers, each of which is closed at the sides and top and has vsuspended therein vertical partitions of filtering medium so arranged as to form of a portion of the space within said chamber vertical 'spaces' which lare en-'- tirely closed except foropenings through whiclrvacunm 'and pressure may be applied thereto, and said chambers arrangedin a ringv and attached to a suitable drivithg and supporting mechanism so as to movethrough thesame horizontal annular path around a central vertical axis; a4 central automatic' part thereof arranged to re valve having a volve around said central vertical axis with said chambers, said revolving part having separate ports therein corresponding to said chambers and connected b suitable pipes to said enclosed spaces in sai chambers and arranged so that vacuum and pressure may be automatically applied to said enclosed spaces in each of said chambers during the passage of said chambers through certain arts of said annular path; an annular troug be neath said annular path with radial partitions therein dividing said trough into separate sectors some of which are arranged to contain liquids and one of which sectors is arranged to receive filter cakes dropped from said chambers; means for passing said chambers over said partitions and allowing the lower parts of said chamber to dip into the liquids in said sectors in passing around said annular path; means for applying vacuum and pressure through said automatic central valve; means for continuously supplying liquid to be filtered to said sectors or containing liquid; all arranged so that when liquid to be filtered is continuously supplied to said sectors for containing liquid and said chambers are continuously moved in one direction around said annular path by the application of power to said i supporting and driving mechanism and o n s vbers and li uid willwbe vacuum rassure are sup lied to said central automatic valve that in t e arts of the path of said chambers above sai sectors containing liquids said liquids will be drawn up into and fill said ces in said chamrawn through said partitions o filter medium into said enclosed spaces and be withdrawn therefrom and solids in suspension in said li uid will forni filter cakes on the sides of said filter media in said openspaces, and in the part of said path above said' discharge sector the filter cakes thus vformed will be discharged from said chambers into said sector.

13. The a paratus for separating liquids from finely ivided solids by filtration which consists of a number of similar vertical chambers each of which is closed at the sides and to and has su ended therein partitions o filtering medium so arranged as to form of a portion of the space within said chamber vertical spaces which are entirely enclosed except for openings through which vacuum and pressure may be applied thereto, and said chambers arranged in a ring and attached to a suitable driving and supporting mechanism so as to move through the same horizontal annular path around a central vertical axis; a central automatic valve havin `a art thereof arranged to revolve aroun said central vertical axis with said chambers, said revolving part having separate ports therein corresponding to said chambers and connected by suitable pipes to said enclosed spaces in said chambers and arranged so that vacuum and pressure. may be automatically applied to said enclosed spaces in each of ysaid chambers during the passage of said vchambers through certain predetermined parts of said annular path; c

an annular trough beneath said annular 4path with radial partitions therein dividing said trough into separate sectors some of which are arranged to contain liquids and l overflow liquid from said overflow sectors to the main sector from which it came, all arranged so as to maintain the liquid in said main lsectors at a level above the bottom of said notches and thel liquid in said overflow sectors at a level below said notches.

14. The apparatus for separating liquids from finely divided solids by filtration which consists of a number of similar vertical chambers, each of which is closed at the sides and topand has suspended therein vertical partitions of filteringmedium so arranged as to form of a portion of the space within said chamber vertical spaces which are entirely enclosed except for openin .qs through which vacuum and preure may be applied thereto` and said cham bers arranged in a ring and attached to a suitable driving and supporting mechanism so as tovmove through the same horizontal annular path around a central vertical axis;

thereof arranged to revolve around said centra] vertical axis with said chambers, said revolving part having separate ports therein va central automatic' valve having a part corresponding to said chambers and connectl ed by suitable pipes to said enclosed spaces in said chambers and arranged so that vacuum and pressure may be automaticallyapplied to said enclosed spaces in each of said chambers during the passage of said chambers through certain predetermined parts of said annular path; an annular trough beneath said annular path with radial partitions therein dividing said trough into separate sectors some of which are arranged to contain liquids and one of which sectors is larranged to receive filter cakes dropped from said chambers, each of said sectors for containing liouids having notches in the upper part of the end partitions thereof arranged so that the lower parts of said chambers memes may pass through said notches in moving around said annular path, and each ofthe said last sectors having an overow lsectorat each end to receive the liquid overdowing through said notch, and means for continuously returning said overfiow liquid from said overflow sectors to the main sector from which it came, all arranged so as to maintain the liquid in said main sector 'at a level-- above the bottom of said notches and above the bot-- tom of said chambers and the liquid in said overflow sectors at a level below seid notches; means for continuously supplying liquid to be ltered to said main sectors for.

containin li uids and means for maintaining the llqui s therein at substantially the same constant level, so thatthe lower parts of said chambers will dip slightly into said liquid in passing over said main sectors; means for applying vacuum and pressure through said automatic central valve.

En testimony whereof I have signed my neme to this s ecicat-ion.

NI LS CQCHRISTENSEN.

sept. l6,1927, E CLARKE 1,641,737

EIQECTRI CAL POWER TRANSMI S SIO N Filed April 30, 1925 Evi.

Edith Clarke, 

